/*
 * $Id: MacOSXPopupLocationFix.java 4019 2011-05-11 16:52:30Z kschaefe $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.jdesktop.swingx.autocomplete.workarounds;

import java.awt.Component;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;

import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JPopupMenu;
import javax.swing.UIManager;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;

/**
 * Fix a problem where the JComboBox's popup obscures its editor in the Mac OS X
 * Aqua look and feel.
 *
 * <p>
 * Installing this fix will resolve the problem for Aqua without having
 * side-effects for other look-and-feels. It also supports dynamically changed
 * look and feels.
 *
 * @see <a
 *      href="https://glazedlists.dev.java.net/issues/show_bug.cgi?id=332">Glazed
 *      Lists bug entry</a>
 * @see <a href="https://swingx.dev.java.net/issues/show_bug.cgi?id=360">SwingX
 *      bug entry</a>
 *
 * @author <a href="mailto:jesse@swank.ca">Jesse Wilson</a>
 */
public final class MacOSXPopupLocationFix {

	/** the components being fixed */
	private final JComboBox comboBox;
	private final JPopupMenu popupMenu;

	/** the listener provides callbacks as necessary */
	private final Listener listener = new Listener();

	/**
	 * Private constructor so users use the more action-oriented
	 * {@link #install} method.
	 */
	private MacOSXPopupLocationFix(JComboBox comboBox) {
		this.comboBox = comboBox;
		this.popupMenu = (JPopupMenu) comboBox.getUI().getAccessibleChild(comboBox, 0);

		popupMenu.addPopupMenuListener(listener);
	}

	/**
	 * Install the fix for the specified combo box.
	 */
	public static MacOSXPopupLocationFix install(JComboBox comboBox) {
		if (comboBox == null)
			throw new IllegalArgumentException();
		return new MacOSXPopupLocationFix(comboBox);
	}

	/**
	 * Uninstall the fix. Usually this is unnecessary since letting the combo
	 * box go out of scope is sufficient.
	 */
	public void uninstall() {
		popupMenu.removePopupMenuListener(listener);
	}

	/**
	 * Reposition the popup immediately before it is shown.
	 */
	private class Listener implements PopupMenuListener {
		@Override
		public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
			final JComponent popupComponent = (JComponent) e.getSource();
			fixPopupLocation(popupComponent);
		}

		@Override
		public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
			// do nothing
		}

		@Override
		public void popupMenuCanceled(PopupMenuEvent e) {
			// do nothing
		}
	}

	/**
	 * Do the adjustment on the specified popupComponent immediately before it
	 * is displayed.
	 */
	private void fixPopupLocation(JComponent popupComponent) {
		// we only need to fix Apple's aqua look and feel
		if (popupComponent.getClass().getName().indexOf("apple.laf") != 0) {
			return;
		}

		// put the popup right under the combo box so it looks like a
		// normal Aqua combo box
		Point comboLocationOnScreen = comboBox.getLocationOnScreen();
		int comboHeight = comboBox.getHeight();
		int popupY = comboLocationOnScreen.y + comboHeight;

		// ...unless the popup overflows the screen, in which case we put it
		// above the combobox
		Rectangle screenBounds = new ScreenGeometry(comboBox).getScreenBounds();
		int popupHeight = popupComponent.getPreferredSize().height;
		if (comboLocationOnScreen.y + comboHeight + popupHeight > screenBounds.x + screenBounds.height) {
			popupY = comboLocationOnScreen.y - popupHeight;
		}

		popupComponent.setLocation(comboLocationOnScreen.x, popupY);
	}

	/**
	 * Figure out the dimensions of our screen.
	 *
	 * <p>
	 * This code is inspired by similar in
	 * <code>JPopupMenu.adjustPopupLocationToFitScreen()</code>.
	 *
	 * @author <a href="mailto:jesse@swank.ca">Jesse Wilson</a>
	 */
	private final static class ScreenGeometry {

		final GraphicsConfiguration graphicsConfiguration;
		final boolean aqua;

		public ScreenGeometry(JComponent component) {
			this.aqua = UIManager.getLookAndFeel().getName().indexOf("Aqua") != -1;
			this.graphicsConfiguration = graphicsConfigurationForComponent(component);
		}

		/**
		 * Get the best graphics configuration for the specified point and
		 * component.
		 */
		private GraphicsConfiguration graphicsConfigurationForComponent(Component component) {
			Point point = component.getLocationOnScreen();

			// try to find the graphics configuration for our point of interest
			GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
			GraphicsDevice[] gd = ge.getScreenDevices();
			for (int i = 0; i < gd.length; i++) {
				if (gd[i].getType() != GraphicsDevice.TYPE_RASTER_SCREEN)
					continue;
				GraphicsConfiguration defaultGraphicsConfiguration = gd[i].getDefaultConfiguration();
				if (!defaultGraphicsConfiguration.getBounds().contains(point))
					continue;
				return defaultGraphicsConfiguration;
			}

			// we couldn't find a graphics configuration, use the component's
			return component.getGraphicsConfiguration();
		}

		/**
		 * Get the bounds of where we can put a popup.
		 */
		public Rectangle getScreenBounds() {
			Rectangle screenSize = getScreenSize();
			Insets screenInsets = getScreenInsets();

			return new Rectangle(screenSize.x + screenInsets.left, screenSize.y + screenInsets.top, screenSize.width
					- screenInsets.left - screenInsets.right, screenSize.height - screenInsets.top - screenInsets.bottom);
		}

		/**
		 * Get the bounds of the screen currently displaying the component.
		 */
		public Rectangle getScreenSize() {
			// get the screen bounds and insets via the graphics configuration
			if (graphicsConfiguration != null) {
				return graphicsConfiguration.getBounds();
			}

			// just use the toolkit bounds, it's less awesome but sufficient
			return new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
		}

		/**
		 * Fetch the screen insets, the off limits areas around the screen such
		 * as menu bar, dock or start bar.
		 */
		public Insets getScreenInsets() {
			Insets screenInsets;
			if (graphicsConfiguration != null) {
				screenInsets = Toolkit.getDefaultToolkit().getScreenInsets(graphicsConfiguration);
			} else {
				screenInsets = new Insets(0, 0, 0, 0);
			}

			// tweak the insets for aqua, they're reported incorrectly there
			if (aqua) {
				int aquaBottomInsets = 21; // unreported insets, shown in
											// screenshot,
											// https://glazedlists.dev.java.net/issues/show_bug.cgi?id=332
				int aquaTopInsets = 22; // for Apple menu bar, found via
										// debugger

				screenInsets.bottom = Math.max(screenInsets.bottom, aquaBottomInsets);
				screenInsets.top = Math.max(screenInsets.top, aquaTopInsets);
			}

			return screenInsets;
		}
	}
}